Safety device for elevators.



NO. 743,923. PATENTEDYNOV. 10,1903.

F" D. POTTER.

.SAEETY DEVICE FOR ELEVATORS.

APPLIO AIION FILED MAR. 4, 1903. I N0 MODEL. 2 SHBETS SHEET 1.

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PATENTED Nov. 10, 1903. F. D. POTTER. SAFETY DEVICE FOR ELEVATORS;

APPLIOATIONTILED MAR. 4, 1903.

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3% A Elam/nag I UNITED STATES FRED ERIC D. POTTER, OF LINDEN, NEW JERSEY.

SAFETY DEVICE FOR ELEVATORS.

SPECIFICATiONf forming part of Letters Patent No. 743,923, dated November 10, 1903. Q

Application filed March 4, 1903.

To all whom it may concern.-

Be it known that I, Fnunnnro D. POTTER, a

citizen of the United States, residing in Lin- The invention is illustrated'ina preferred form in the accompanying drawings, where- I in-'- Figure l is a vertical sectional view on the line at a: in Fig. 2, and Fig. 2 is a horizontal section on a plane immediately below the carfioor.

- As ordinarily constructed elevators of the class above named are provided with counterweights of sufficient size not only to balance the weight of the car, but also to partly balance that of the plunger. It is obvious that in case the plunger should break the counterweight wouid throw the car to the top of the shaft with disastrous. results and that the lower fragment of the plunger continuing to move upward and being unrestrained at its upper end would very probably create dam-.

age in the shaft. My invention obviates both of these difliculties.

In the drawings the car is shown at 1, supported by a hollow steel plunger 2, which moves within a cylinder 3 in the usual manner.

It is of the essence of this invention that the hollow plunger shall be filled with. fluid under compression and that means shall be provided for supporting the car, which meansare normally prevented from operation by the pressure of the fluid within the plunger.

The usual guides for the car are shown at 4 in Fig. 2, and beneath the car I mount two pairs of jaws 5, pivoted, as at 6, and adapted to be forcibly closed upon the guides 4: by api- Serial No. 146,073. (No model.)

propiate levers under the influence of a spring '7 or equivalent means.

As shown in Fig. 2,the spring 7 acts,through toggle jaws and levers acting on both sides thereof, to close thejaws 5. The rack-bar 8 :is attached to the aforesaid lever system, so as to move in the direction of the arrow in Fig. 2 when the jaws are closed. The rack Sengages with the pinion 9, to which is attached the ratchet 10, controlled by the pawl 11,.pivoted at 12. The pawl is held normally in engagement with the ratchet 10 by the spring 13.

the use of means tending constantly to push the pawl 11 out of engagement with the ratchet l0, and this means is combined with a device forpreventing operation of said means as long as the predetermined fluid-pressure is preserved within the plunger 2. I l Vith these ends in view I use areciprocating rod 14:, carrying an adjustable abutment l5,'so arranged as to press upon the pawl 11 for causing disengagement with the ratchet 10 when said rod and abutment are pushed to the left in Fig. 2. The preferred means employed for so pushing the rod lei consists of a diaphragm '16 within an appropriate chamber 17, which communicates by a pipe 18 with a chamber '19. This chamber 19 is supplied with fluid under pressure (preferably air) from the plunger 2 through a pipe 20, into which is inserted chamber 19, but not to leave it.

It is obvious that if the plunger with compressed air under a pressure of, say, two hundred pounds to theinch the chamber 19 will be charged with air at the same presplunger 2 the check-valve 21 will prevent a 'like fall of pressure in the chamber 19. The device for counteracting the tendency of the diaphragm 16 preferably comprises 2. diaphragm 22 Within an appropriate chamber 23. This chamber communicates with the plunger 2 by means of the pipe 24. Normally the pressure per square inch is equal on the left of diaphragm 22 and on the right of diaphragm 16; but since the diaphragm 22 is the My invention involves in its preferred form a check-valve 21, permitting. air to enter the 2 is filled sure; but in case of failure of pressure in the larger of the two it determines the position of the abutment 15, and thus insures engagement between the pawl 11 and ratchet 10.

The arrangement shown permits of a con siderable loss of pressure in the plunger 2 and the chamber 23 by reason of leakage before the diaphragm 16 is able to overpower the diaphragm 22, and thus such variations in pressure as cannot be avoided in practice will not cause danger of accidental and inopportune operation of the jaws 5.

In Fig. 1 there isshowna pressure-gage 25, which connects with the plunger 2 by the pipe 26, whereby the operator can ascertain how nearly any reduction in pressure is approaching the critical condition which causes operation of the clutch. The pressure can always be brought back to a safe amount by an aircompressor connected to the valve 27.

It is to be understood that the diaphragm 16 and its associated parts can be replaced by any desired device causing constant pressure against the diaphragm 22 without departing from this invention.

After operation of the safety-jaws their grip can be released by'applying an appropriate key28 to a square 29 from the pinion and ratchet 9 and 10.

I prefer to employ an opening 30, preferably covered with a flat valve, at the bottom of the plunger 2, as shown in Fig. 1. The water in the cylinder 3 will be prevented from entering the plunger in any material quantity by the compressed air within the plunger, and in case of entrance of water to an undesirable extent the same may be blownout by opening the valve 31 in the pipe 32 within the plunger.

Supposing the plunger to be broken at any time, the fluid under pressure therein will be liberated and the following actions will be produced: The pressure in the chamber 23 will fall to atmosphere and the diaphragm 16, pushing the abutment 15 to the left in Fig. 2, will throw the pawl 11 out of engagement with the ratchet, permitting the spring 7 to apply the jaws 5 to the guides 4, thus holding the car rigidly in place in the shaft. At the same time the water under pressurein the cylinder 3 will be forced through the opening 30, allowing the plunger 2 to sink without further damage than the overflow of waterfrom the cylinder. Thus neither the car nor the broken plunger will cause disaster.

Many changes may be made in the various possible arrangements which I have set forth without departing from this invention, and I am not to be understood as limiting myself to the details herein shown and described.

What I claim is 1. An elevator-car, a hollow plunger containing fluid under constant pressure supporting said car and means for raising said plunger; in combination with means on the car controlled by said fluid under pressure for securing the car in its shaft, substantially as described.

2. An elevator-car, a hollow plunger supporting the same .and a hydraulic cylinder within which said plunger can move said plunger containing fluid under a constant pressure, by leakage of which the faults in the plunger can be detected.

3. An elevator-car, a hollow plunger supporting the same and means for raising said plunger; in combination with securing means for the car adapted for operation by fluid under pressure and connecting-pipes connecting said means with the interior of said plunger, substantially as described.

4. In an elevator, a hollow ear-supporting plunger containing fluid normally under constant pressure, a hydraulic cylinder therefor, and a valve admitting water'to said plunger when the interior fluid-pressure permits, substantially as described.

5. In an elevator, a hollow car=supporting plunger, a hydraulic cylinder therefor, a

valve admitting water to said plunger and a blow-0E pipe leading from a point within and near the bottom of said plunger to the exterior thereof, substantially as described.

6. An elevator-car, a hollow plunger supporting the same, a securing means for the car carried thereby, means for operating said securing means, a device for restraining said operating means and a device controlled by fluid-pressure within said plunger for removing said restraining device, substantially as described.

7. An elevator-car, a hollow plunger supporting the same, a securing means for the car carried thereby, means tending constantly to operate said securing means, a device tending constantly to free said operating means and a pressure device controlled by fluidpressure within said plunger for normally preventing action of said tripping device, substantially as described.

8. An elevator-car, a hollow plunger supporting the same, a safety device controlled by fluid-pressure within said plunger, a connecting-valve for applying a fluid-compressor to said plunger and a gage connected to said plunger for measuring the fluid pressure within it, substantially as described.

9. An elevator-car, guides therefor, movable jaws for gripping said guides, a hollow plunger containing a fluid under constant pressure supporting the car, means for operating the gripping-jaws and a device operated by the fluid-pressure in said plunger for controlling said operating means, substantially as described.

10. An elevator-car, a safety device thereon, a tripping device therefor, a hollow plunger supporting the car, a diaphragm and fluid-reservoir tending to operate the tripping device and a second opposing diaphragm operated by fluid-pressure within said plunger, substantially as described.

11. An elevator-car, a safety device therefor, a tripping device therefor, a hollow plunger supporting the car, a fluid-reservoir communicating with said plunger through a check-valve, a diaphragmoperatedby pressure in said reservoir for moving the trip.- 1

ping device, and a larger diaphragm con- {0 nected directly with said plunger and opposing the tendency of the smaller diaphragm,

substantially as described.

FREDEBIO D. POTTER.

Witnesses:

H. S. MAcKAYE, JOHN MOKAY. 

